A series of 1-[2-(1,8-diethyl-1,3,4,9-tetrahydropyrano[3,4-b]indol-1- yl)acetyl]-4-alkyl/aryl thiosemicarbazides and 5-[(1,8-di- ethyl-1,3,4,9-tetrahydropyrano[3,4-b]indol-1-yl)methyl]-4-substitut- ed-2,4-dihydro-3H-1,2,4-triazole-3-thiones have been synthesized. Inhibition of hepatitis C virus NS58 RNA dependent RNA polymerase activity by these compounds was evaluated.